1. Field of the Invention
This invention relates to lavatory cleansing devices for delivering fragrance and cleansing products to a lavatory bowl. The invention is particularly concerned with devices delivering a liquid product such as a perfume, surfactant or disinfectant, particularly in the form of a solution, dispersion or suspension, together with a bleach, or other relatively aggressive product such as a limescale remover, and for delivering it to a toilet bowl under the action of water used to flush the toilet bowl.
2. Description of the Prior Art
It has been known for a long time to provide so-called toilet automatics in the form of a solid or semi-solid product, a ‘rim block’, to be mounted within the inner rim of a water closet bowl where the flushing water will wash over the product and so dissolve or erode it to release active constituents into the water flow. Blocks may also be placed on top of the cistern in Japanese style systems where water from a tap flows over the block and then into the cistern, and also may be placed within the cistern below the water level, where they slowly release constituents into the water.
These products have long been used to deliver a surfactant, a perfume and a dye to the toilet bowl. The surfactant provides a cleaning action, while the dye and perfume provide a visual and olfactory indication to the user that some cleansing effect is being achieved. Much effort has also been put into formulating rim blocks which will also deliver a bleaching agent, such as sodium dichloroisocyanurate, to the toilet bowl and these have been successfully developed and marketed by the present applicants.
Different considerations apply when formulating products which dose the water in the cistern and products which dose directly into the toilet bowl. With a solid block, the block will be completely immersed in water when used in the cistern, but will be exposed only intermittently to flush water when used in the toilet bowl.
Many different mechanisms have been proposed for dosing solid or liquid formulations into the cistern, making use of movement of water in the cistern. For dosing directly into the toilet bowl, the long used system has been a solid block which is housed in a cage suspended in the path of the flush water as it enters the bowl.
More recently, products have been developed for dosing a liquid toilet freshening product directly into the toilet bowl, in a similar manner to rim blocks, providing a so-called liquid rim product. For example, EP-A-0 538 957 describes a device that can be mounted on the inner rim of a water closet bowl to dose a liquid freshening product into the flushing water. In this device, the liquid product is dosed into the water flow from a porous substrate, forming a delivery plate which is disposed in the path of the flushing water. The porous substrate is supplied with the liquid product from a container disposed above the substrate, a mouth at the bottom of the container has a liquid permeable plug which opens onto the upper surface of the substrate.
EP-A-0 785 315 describes a development of the device discussed above. The same basic principle of delivering a liquid product into a flow of water from a porous substrate is employed. However, liquid product from the container is deposited onto the upper surface of the substrate via a regulating channel. The liquid is metered into the channel through an orifice and a separate opening allowing air into the interior of the container is provided. The sizes of the metering orifice and the air opening are related to the viscosity of the liquid being dosed.
WO 99/66139 and WO 99/66140 describe numerous variations of the liquid rim product, including different styles of delivery plate in place of the porous plate of EP-A-0 538 957, while WO 00/42261 describes a design which uses a grooved plate.
All of the above systems use the same basic idea of delivering liquid directly from the container's mouth onto the delivery plate.
Further developments of the liquid rim system are described in co-pending applications Nos. GB 0026832.6 and WO 01/32995 which are incorporated herein by reference.
EP-A-775 741 describes a liquid formulation suitable for use in liquid rim products. This formulation comprises perfume, anionic or non-ionic surfactant, evaporation regulator and a solvent. EP-A-775 741 also mentions that a bleaching or disinfecting agent, such as hypochlorite, peroxide or isocyanurate can be incorporated in the liquid formulation but no actual formulation is described.
A problem with bleach formulations, whether of the liquid or solid type, is that the bleach can have an adverse effect on other constituents in the formulation and on the delivery device itself, particularly where it is desirable to use a transparent container so that the user can see the color of the formulation, and can also see when the supply is nearly exhausted and a refill is required. For example, good quality perfumes are not compatible with bleaches. Typically, PVC and PET are used for moulding liquid rim devices, but high density polyethylene or polypropylene would be preferred materials for a bleach system.